In internal combustion engines with variable compression, as are described in DE 10 2012 008 244 A1 for example, engine damage and a negative influence on exhaust gas can occur when the actual compression does not correspond to the desired compression. The variable compression is usually controlled by a control circuit, wherein a sensor signal which is indicative of the compression is used as a feedback signal in order to control an actuating variable for an actuator with which the compression is adjusted.